Japanese patent application publication No. 2004-034722 discloses a printer that prints an image on a printing medium based on image data. This printer includes a platen having a contact part for contacting and supporting the printing medium as the printing medium is conveyed in a sub scanning direction. A groove part that does not contact the recording medium is also formed in the platen on the downstream side of the contact part relative to the sub scanning direction. The printer includes a print head for forming images on the recording media by ejecting ink droplets from a plurality of nozzles formed in the print head. These nozzles include a first nozzle group that opposes the contact part of the platen and a second nozzle group that opposes the groove part of the platen as the print head is conveyed in a main scanning direction.
With the printer described in Japanese patent application publication No. 2004-034722, ink droplets are ejected from both the first and second nozzle groups when printing a center image portion of the image in the center region of the recording medium with respect to the sub scanning direction. However, ink droplets are ejected only from the second nozzle group when forming edge image parts (constituting edges of an image) in either upstream or downstream edge regions of the recording medium with respect to the sub scanning direction. With this configuration, if the recording medium is not present at the position opposite the second nozzle group when ink droplets are ejected from the second nozzle group to print the edge image part due to error in conveying the recording medium, these ejected ink droplets will be deposited in the groove part of the platen rather than on the contact part. Accordingly, a recording medium that subsequently contacts the contact part will not be soiled by ink since ink droplets are not deposited on the contact part of the platen.